1. Field of the Invention
This invention relates to materials handling apparatus adaptable for mounting on a conventional earth working machine and more particularly to a loader bucket assembly that includes a carrier portion pivotally mounted on the boom of the earth working machine and a bucket portion pivotally connected to the carrier portion and operable through a control system to automatically carry out the discharging cycle of the loader bucket assembly.
2. Description of the Prior Art
Conventional bucket type loaders or excavating buckets generally include a bucket portion defined by a horizontal bottom wall with a transverse cutting edge extending forwardly from the bottom wall. A rear wall extends upwardly in a curved arc from the rear of the bottom wall and terminates in an upper transverse edge spaced above the lower transverse cutting edge. Laterally spaced vertical sidewalls are secured to and extend between the sides of the bottom and rear walls. Generally, with conventional loaders, a bucket portion is supported by a carrier portion that is rigidly secured to the bucket portion and includes a pair of forwardly extending parallel spaced arm members that are secured to and positioned laterally of the bucket sidewalls. The rearward portion of the arm members is pivotally connected to the forward end portion of lift booms of a tractor or earth working machine. The lift booms are pivotal through a vertical arcuate path about a pivotal axis on the tractor by operation of manually controlled piston cylinder assemblies. With this arrangement, the carrier portion, together with the bucket, is raised and lowered by the lift booms. Tilt cylinders extending from the lift booms of the tractor are forwardly connected to the rear wall of the bucket or to the frame of the carrier secured to the rear wall of the bucket. Operation of the tilt cylinders effects pivoting and/or tilting of the bucket relative to the front end of the lift booms and the tractor.
It is also known, with high lift bucket type loaders, to pivotally mount the bucket portion to the carrier portion. With this arrangement, it is customary procedure to first vertically raise the entire assembly to a preselected vertical height through one manual control. This followed by manual actuation of a second control to forwardly pivot or tilt the bucket and carrier portions combined. A third manual control is then actuated to effect pivoting or roll of the bucket portion on the carrier portion to completely discharge the contents of the bucket portion. The manual operation of these respective controls requires that the operator exercise his own judgment as to the completion of one cycle before another can be initiated. Once the bucket portion is loaded actuation of the first control raises lift booms to move the bucket to a maximum vertical height at which it is to be discharged. When this step is completed tilt cylinders are actuated by manually operating a second control lever to forwardly pivot the bucket portion on the carrier portion and move the bucket portion to a first discharging position. The third operation is commenced when the operator has determined that the carrier portion has been fully pivoted. This is difficult to determine, particularly when the bucket is raised to the maximum vertical height for high lift operations. With some arrangements an indicator alerts the operator as to the completion of the carrier tilt so that he may initiate the bucket roll. The bucket roll on the carrier is commenced by operating a third control lever; however, the carrier tilt must be completed before the third control lever is actuated.
It is known with loaders, particularly with side dump loaders as disclosed in U.S. Pat. No. 3,207,342, to provide hydraulic cylinders that operate sequentially to complete the side dumping operation. With this arrangement, a loading bucket is retained in a predumping position on a carrier or frame by a latch. The loaded bucket is raised by one lever to a vertical dumping position. Then, in sequential order, a pair of cylinders is operated to first provide for operation of the latching mechanism to fully release the bucket from its predumping position. Upon release, actuation of the second cylinder operates the side dumping mechanism to pivot the bucket to a dumping position. Hydraulic fluid is supplied to both cylinders simultaneously by the same operating valve.
There is need to provide a loader bucket assembly that is readily adaptable for installation on conventional earth working machines to increase the capacity of the machine without an accompanying loss in vertical dump height and machine stability. The loader bucket must be easily mounted on the earth working machine to facilitate the conversion on the machine from a smaller bucket assembly to an enlarged bucket assembly. The combination of the loader bucket and earth working machine should be efficiently operated by reducing the number of controls which the operator must maneuver and monitor in order to carry out a complete cycle of operation from loading, hauling to discharging. This should be accomplished by a control system that is economically and efficiently operated.